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Commit | Line | Data |
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2b281117 SJ |
1 | /* |
2 | * zswap.c - zswap driver file | |
3 | * | |
4 | * zswap is a backend for frontswap that takes pages that are in the process | |
5 | * of being swapped out and attempts to compress and store them in a | |
6 | * RAM-based memory pool. This can result in a significant I/O reduction on | |
7 | * the swap device and, in the case where decompressing from RAM is faster | |
8 | * than reading from the swap device, can also improve workload performance. | |
9 | * | |
10 | * Copyright (C) 2012 Seth Jennings <sjenning@linux.vnet.ibm.com> | |
11 | * | |
12 | * This program is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU General Public License | |
14 | * as published by the Free Software Foundation; either version 2 | |
15 | * of the License, or (at your option) any later version. | |
16 | * | |
17 | * This program is distributed in the hope that it will be useful, | |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
20 | * GNU General Public License for more details. | |
21 | */ | |
22 | ||
23 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
24 | ||
25 | #include <linux/module.h> | |
26 | #include <linux/cpu.h> | |
27 | #include <linux/highmem.h> | |
28 | #include <linux/slab.h> | |
29 | #include <linux/spinlock.h> | |
30 | #include <linux/types.h> | |
31 | #include <linux/atomic.h> | |
32 | #include <linux/frontswap.h> | |
33 | #include <linux/rbtree.h> | |
34 | #include <linux/swap.h> | |
35 | #include <linux/crypto.h> | |
36 | #include <linux/mempool.h> | |
37 | #include <linux/zbud.h> | |
38 | ||
39 | #include <linux/mm_types.h> | |
40 | #include <linux/page-flags.h> | |
41 | #include <linux/swapops.h> | |
42 | #include <linux/writeback.h> | |
43 | #include <linux/pagemap.h> | |
44 | ||
45 | /********************************* | |
46 | * statistics | |
47 | **********************************/ | |
48 | /* Number of memory pages used by the compressed pool */ | |
49 | static u64 zswap_pool_pages; | |
50 | /* The number of compressed pages currently stored in zswap */ | |
51 | static atomic_t zswap_stored_pages = ATOMIC_INIT(0); | |
52 | ||
53 | /* | |
54 | * The statistics below are not protected from concurrent access for | |
55 | * performance reasons so they may not be a 100% accurate. However, | |
56 | * they do provide useful information on roughly how many times a | |
57 | * certain event is occurring. | |
58 | */ | |
59 | ||
60 | /* Pool limit was hit (see zswap_max_pool_percent) */ | |
61 | static u64 zswap_pool_limit_hit; | |
62 | /* Pages written back when pool limit was reached */ | |
63 | static u64 zswap_written_back_pages; | |
64 | /* Store failed due to a reclaim failure after pool limit was reached */ | |
65 | static u64 zswap_reject_reclaim_fail; | |
66 | /* Compressed page was too big for the allocator to (optimally) store */ | |
67 | static u64 zswap_reject_compress_poor; | |
68 | /* Store failed because underlying allocator could not get memory */ | |
69 | static u64 zswap_reject_alloc_fail; | |
70 | /* Store failed because the entry metadata could not be allocated (rare) */ | |
71 | static u64 zswap_reject_kmemcache_fail; | |
72 | /* Duplicate store was encountered (rare) */ | |
73 | static u64 zswap_duplicate_entry; | |
74 | ||
75 | /********************************* | |
76 | * tunables | |
77 | **********************************/ | |
78 | /* Enable/disable zswap (disabled by default, fixed at boot for now) */ | |
79 | static bool zswap_enabled __read_mostly; | |
80 | module_param_named(enabled, zswap_enabled, bool, 0); | |
81 | ||
82 | /* Compressor to be used by zswap (fixed at boot for now) */ | |
83 | #define ZSWAP_COMPRESSOR_DEFAULT "lzo" | |
84 | static char *zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT; | |
85 | module_param_named(compressor, zswap_compressor, charp, 0); | |
86 | ||
87 | /* The maximum percentage of memory that the compressed pool can occupy */ | |
88 | static unsigned int zswap_max_pool_percent = 20; | |
89 | module_param_named(max_pool_percent, | |
90 | zswap_max_pool_percent, uint, 0644); | |
91 | ||
92 | /********************************* | |
93 | * compression functions | |
94 | **********************************/ | |
95 | /* per-cpu compression transforms */ | |
96 | static struct crypto_comp * __percpu *zswap_comp_pcpu_tfms; | |
97 | ||
98 | enum comp_op { | |
99 | ZSWAP_COMPOP_COMPRESS, | |
100 | ZSWAP_COMPOP_DECOMPRESS | |
101 | }; | |
102 | ||
103 | static int zswap_comp_op(enum comp_op op, const u8 *src, unsigned int slen, | |
104 | u8 *dst, unsigned int *dlen) | |
105 | { | |
106 | struct crypto_comp *tfm; | |
107 | int ret; | |
108 | ||
109 | tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, get_cpu()); | |
110 | switch (op) { | |
111 | case ZSWAP_COMPOP_COMPRESS: | |
112 | ret = crypto_comp_compress(tfm, src, slen, dst, dlen); | |
113 | break; | |
114 | case ZSWAP_COMPOP_DECOMPRESS: | |
115 | ret = crypto_comp_decompress(tfm, src, slen, dst, dlen); | |
116 | break; | |
117 | default: | |
118 | ret = -EINVAL; | |
119 | } | |
120 | ||
121 | put_cpu(); | |
122 | return ret; | |
123 | } | |
124 | ||
125 | static int __init zswap_comp_init(void) | |
126 | { | |
127 | if (!crypto_has_comp(zswap_compressor, 0, 0)) { | |
128 | pr_info("%s compressor not available\n", zswap_compressor); | |
129 | /* fall back to default compressor */ | |
130 | zswap_compressor = ZSWAP_COMPRESSOR_DEFAULT; | |
131 | if (!crypto_has_comp(zswap_compressor, 0, 0)) | |
132 | /* can't even load the default compressor */ | |
133 | return -ENODEV; | |
134 | } | |
135 | pr_info("using %s compressor\n", zswap_compressor); | |
136 | ||
137 | /* alloc percpu transforms */ | |
138 | zswap_comp_pcpu_tfms = alloc_percpu(struct crypto_comp *); | |
139 | if (!zswap_comp_pcpu_tfms) | |
140 | return -ENOMEM; | |
141 | return 0; | |
142 | } | |
143 | ||
144 | static void zswap_comp_exit(void) | |
145 | { | |
146 | /* free percpu transforms */ | |
147 | if (zswap_comp_pcpu_tfms) | |
148 | free_percpu(zswap_comp_pcpu_tfms); | |
149 | } | |
150 | ||
151 | /********************************* | |
152 | * data structures | |
153 | **********************************/ | |
154 | /* | |
155 | * struct zswap_entry | |
156 | * | |
157 | * This structure contains the metadata for tracking a single compressed | |
158 | * page within zswap. | |
159 | * | |
160 | * rbnode - links the entry into red-black tree for the appropriate swap type | |
161 | * refcount - the number of outstanding reference to the entry. This is needed | |
162 | * to protect against premature freeing of the entry by code | |
163 | * concurent calls to load, invalidate, and writeback. The lock | |
164 | * for the zswap_tree structure that contains the entry must | |
165 | * be held while changing the refcount. Since the lock must | |
166 | * be held, there is no reason to also make refcount atomic. | |
167 | * offset - the swap offset for the entry. Index into the red-black tree. | |
168 | * handle - zsmalloc allocation handle that stores the compressed page data | |
169 | * length - the length in bytes of the compressed page data. Needed during | |
170 | * decompression | |
171 | */ | |
172 | struct zswap_entry { | |
173 | struct rb_node rbnode; | |
174 | pgoff_t offset; | |
175 | int refcount; | |
176 | unsigned int length; | |
177 | unsigned long handle; | |
178 | }; | |
179 | ||
180 | struct zswap_header { | |
181 | swp_entry_t swpentry; | |
182 | }; | |
183 | ||
184 | /* | |
185 | * The tree lock in the zswap_tree struct protects a few things: | |
186 | * - the rbtree | |
187 | * - the refcount field of each entry in the tree | |
188 | */ | |
189 | struct zswap_tree { | |
190 | struct rb_root rbroot; | |
191 | spinlock_t lock; | |
192 | struct zbud_pool *pool; | |
193 | }; | |
194 | ||
195 | static struct zswap_tree *zswap_trees[MAX_SWAPFILES]; | |
196 | ||
197 | /********************************* | |
198 | * zswap entry functions | |
199 | **********************************/ | |
200 | static struct kmem_cache *zswap_entry_cache; | |
201 | ||
202 | static int zswap_entry_cache_create(void) | |
203 | { | |
204 | zswap_entry_cache = KMEM_CACHE(zswap_entry, 0); | |
205 | return (zswap_entry_cache == NULL); | |
206 | } | |
207 | ||
208 | static void zswap_entry_cache_destory(void) | |
209 | { | |
210 | kmem_cache_destroy(zswap_entry_cache); | |
211 | } | |
212 | ||
213 | static struct zswap_entry *zswap_entry_cache_alloc(gfp_t gfp) | |
214 | { | |
215 | struct zswap_entry *entry; | |
216 | entry = kmem_cache_alloc(zswap_entry_cache, gfp); | |
217 | if (!entry) | |
218 | return NULL; | |
219 | entry->refcount = 1; | |
220 | return entry; | |
221 | } | |
222 | ||
223 | static void zswap_entry_cache_free(struct zswap_entry *entry) | |
224 | { | |
225 | kmem_cache_free(zswap_entry_cache, entry); | |
226 | } | |
227 | ||
228 | /* caller must hold the tree lock */ | |
229 | static void zswap_entry_get(struct zswap_entry *entry) | |
230 | { | |
231 | entry->refcount++; | |
232 | } | |
233 | ||
234 | /* caller must hold the tree lock */ | |
235 | static int zswap_entry_put(struct zswap_entry *entry) | |
236 | { | |
237 | entry->refcount--; | |
238 | return entry->refcount; | |
239 | } | |
240 | ||
241 | /********************************* | |
242 | * rbtree functions | |
243 | **********************************/ | |
244 | static struct zswap_entry *zswap_rb_search(struct rb_root *root, pgoff_t offset) | |
245 | { | |
246 | struct rb_node *node = root->rb_node; | |
247 | struct zswap_entry *entry; | |
248 | ||
249 | while (node) { | |
250 | entry = rb_entry(node, struct zswap_entry, rbnode); | |
251 | if (entry->offset > offset) | |
252 | node = node->rb_left; | |
253 | else if (entry->offset < offset) | |
254 | node = node->rb_right; | |
255 | else | |
256 | return entry; | |
257 | } | |
258 | return NULL; | |
259 | } | |
260 | ||
261 | /* | |
262 | * In the case that a entry with the same offset is found, a pointer to | |
263 | * the existing entry is stored in dupentry and the function returns -EEXIST | |
264 | */ | |
265 | static int zswap_rb_insert(struct rb_root *root, struct zswap_entry *entry, | |
266 | struct zswap_entry **dupentry) | |
267 | { | |
268 | struct rb_node **link = &root->rb_node, *parent = NULL; | |
269 | struct zswap_entry *myentry; | |
270 | ||
271 | while (*link) { | |
272 | parent = *link; | |
273 | myentry = rb_entry(parent, struct zswap_entry, rbnode); | |
274 | if (myentry->offset > entry->offset) | |
275 | link = &(*link)->rb_left; | |
276 | else if (myentry->offset < entry->offset) | |
277 | link = &(*link)->rb_right; | |
278 | else { | |
279 | *dupentry = myentry; | |
280 | return -EEXIST; | |
281 | } | |
282 | } | |
283 | rb_link_node(&entry->rbnode, parent, link); | |
284 | rb_insert_color(&entry->rbnode, root); | |
285 | return 0; | |
286 | } | |
287 | ||
288 | /********************************* | |
289 | * per-cpu code | |
290 | **********************************/ | |
291 | static DEFINE_PER_CPU(u8 *, zswap_dstmem); | |
292 | ||
293 | static int __zswap_cpu_notifier(unsigned long action, unsigned long cpu) | |
294 | { | |
295 | struct crypto_comp *tfm; | |
296 | u8 *dst; | |
297 | ||
298 | switch (action) { | |
299 | case CPU_UP_PREPARE: | |
300 | tfm = crypto_alloc_comp(zswap_compressor, 0, 0); | |
301 | if (IS_ERR(tfm)) { | |
302 | pr_err("can't allocate compressor transform\n"); | |
303 | return NOTIFY_BAD; | |
304 | } | |
305 | *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = tfm; | |
306 | dst = kmalloc(PAGE_SIZE * 2, GFP_KERNEL); | |
307 | if (!dst) { | |
308 | pr_err("can't allocate compressor buffer\n"); | |
309 | crypto_free_comp(tfm); | |
310 | *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL; | |
311 | return NOTIFY_BAD; | |
312 | } | |
313 | per_cpu(zswap_dstmem, cpu) = dst; | |
314 | break; | |
315 | case CPU_DEAD: | |
316 | case CPU_UP_CANCELED: | |
317 | tfm = *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu); | |
318 | if (tfm) { | |
319 | crypto_free_comp(tfm); | |
320 | *per_cpu_ptr(zswap_comp_pcpu_tfms, cpu) = NULL; | |
321 | } | |
322 | dst = per_cpu(zswap_dstmem, cpu); | |
323 | kfree(dst); | |
324 | per_cpu(zswap_dstmem, cpu) = NULL; | |
325 | break; | |
326 | default: | |
327 | break; | |
328 | } | |
329 | return NOTIFY_OK; | |
330 | } | |
331 | ||
332 | static int zswap_cpu_notifier(struct notifier_block *nb, | |
333 | unsigned long action, void *pcpu) | |
334 | { | |
335 | unsigned long cpu = (unsigned long)pcpu; | |
336 | return __zswap_cpu_notifier(action, cpu); | |
337 | } | |
338 | ||
339 | static struct notifier_block zswap_cpu_notifier_block = { | |
340 | .notifier_call = zswap_cpu_notifier | |
341 | }; | |
342 | ||
343 | static int zswap_cpu_init(void) | |
344 | { | |
345 | unsigned long cpu; | |
346 | ||
347 | get_online_cpus(); | |
348 | for_each_online_cpu(cpu) | |
349 | if (__zswap_cpu_notifier(CPU_UP_PREPARE, cpu) != NOTIFY_OK) | |
350 | goto cleanup; | |
351 | register_cpu_notifier(&zswap_cpu_notifier_block); | |
352 | put_online_cpus(); | |
353 | return 0; | |
354 | ||
355 | cleanup: | |
356 | for_each_online_cpu(cpu) | |
357 | __zswap_cpu_notifier(CPU_UP_CANCELED, cpu); | |
358 | put_online_cpus(); | |
359 | return -ENOMEM; | |
360 | } | |
361 | ||
362 | /********************************* | |
363 | * helpers | |
364 | **********************************/ | |
365 | static bool zswap_is_full(void) | |
366 | { | |
367 | return (totalram_pages * zswap_max_pool_percent / 100 < | |
368 | zswap_pool_pages); | |
369 | } | |
370 | ||
371 | /* | |
372 | * Carries out the common pattern of freeing and entry's zsmalloc allocation, | |
373 | * freeing the entry itself, and decrementing the number of stored pages. | |
374 | */ | |
375 | static void zswap_free_entry(struct zswap_tree *tree, struct zswap_entry *entry) | |
376 | { | |
377 | zbud_free(tree->pool, entry->handle); | |
378 | zswap_entry_cache_free(entry); | |
379 | atomic_dec(&zswap_stored_pages); | |
380 | zswap_pool_pages = zbud_get_pool_size(tree->pool); | |
381 | } | |
382 | ||
383 | /********************************* | |
384 | * writeback code | |
385 | **********************************/ | |
386 | /* return enum for zswap_get_swap_cache_page */ | |
387 | enum zswap_get_swap_ret { | |
388 | ZSWAP_SWAPCACHE_NEW, | |
389 | ZSWAP_SWAPCACHE_EXIST, | |
390 | ZSWAP_SWAPCACHE_NOMEM | |
391 | }; | |
392 | ||
393 | /* | |
394 | * zswap_get_swap_cache_page | |
395 | * | |
396 | * This is an adaption of read_swap_cache_async() | |
397 | * | |
398 | * This function tries to find a page with the given swap entry | |
399 | * in the swapper_space address space (the swap cache). If the page | |
400 | * is found, it is returned in retpage. Otherwise, a page is allocated, | |
401 | * added to the swap cache, and returned in retpage. | |
402 | * | |
403 | * If success, the swap cache page is returned in retpage | |
404 | * Returns 0 if page was already in the swap cache, page is not locked | |
405 | * Returns 1 if the new page needs to be populated, page is locked | |
406 | * Returns <0 on error | |
407 | */ | |
408 | static int zswap_get_swap_cache_page(swp_entry_t entry, | |
409 | struct page **retpage) | |
410 | { | |
411 | struct page *found_page, *new_page = NULL; | |
822518dc | 412 | struct address_space *swapper_space = swap_address_space(entry); |
2b281117 SJ |
413 | int err; |
414 | ||
415 | *retpage = NULL; | |
416 | do { | |
417 | /* | |
418 | * First check the swap cache. Since this is normally | |
419 | * called after lookup_swap_cache() failed, re-calling | |
420 | * that would confuse statistics. | |
421 | */ | |
422 | found_page = find_get_page(swapper_space, entry.val); | |
423 | if (found_page) | |
424 | break; | |
425 | ||
426 | /* | |
427 | * Get a new page to read into from swap. | |
428 | */ | |
429 | if (!new_page) { | |
430 | new_page = alloc_page(GFP_KERNEL); | |
431 | if (!new_page) | |
432 | break; /* Out of memory */ | |
433 | } | |
434 | ||
435 | /* | |
436 | * call radix_tree_preload() while we can wait. | |
437 | */ | |
438 | err = radix_tree_preload(GFP_KERNEL); | |
439 | if (err) | |
440 | break; | |
441 | ||
442 | /* | |
443 | * Swap entry may have been freed since our caller observed it. | |
444 | */ | |
445 | err = swapcache_prepare(entry); | |
446 | if (err == -EEXIST) { /* seems racy */ | |
447 | radix_tree_preload_end(); | |
448 | continue; | |
449 | } | |
450 | if (err) { /* swp entry is obsolete ? */ | |
451 | radix_tree_preload_end(); | |
452 | break; | |
453 | } | |
454 | ||
455 | /* May fail (-ENOMEM) if radix-tree node allocation failed. */ | |
456 | __set_page_locked(new_page); | |
457 | SetPageSwapBacked(new_page); | |
458 | err = __add_to_swap_cache(new_page, entry); | |
459 | if (likely(!err)) { | |
460 | radix_tree_preload_end(); | |
461 | lru_cache_add_anon(new_page); | |
462 | *retpage = new_page; | |
463 | return ZSWAP_SWAPCACHE_NEW; | |
464 | } | |
465 | radix_tree_preload_end(); | |
466 | ClearPageSwapBacked(new_page); | |
467 | __clear_page_locked(new_page); | |
468 | /* | |
469 | * add_to_swap_cache() doesn't return -EEXIST, so we can safely | |
470 | * clear SWAP_HAS_CACHE flag. | |
471 | */ | |
472 | swapcache_free(entry, NULL); | |
473 | } while (err != -ENOMEM); | |
474 | ||
475 | if (new_page) | |
476 | page_cache_release(new_page); | |
477 | if (!found_page) | |
478 | return ZSWAP_SWAPCACHE_NOMEM; | |
479 | *retpage = found_page; | |
480 | return ZSWAP_SWAPCACHE_EXIST; | |
481 | } | |
482 | ||
483 | /* | |
484 | * Attempts to free an entry by adding a page to the swap cache, | |
485 | * decompressing the entry data into the page, and issuing a | |
486 | * bio write to write the page back to the swap device. | |
487 | * | |
488 | * This can be thought of as a "resumed writeback" of the page | |
489 | * to the swap device. We are basically resuming the same swap | |
490 | * writeback path that was intercepted with the frontswap_store() | |
491 | * in the first place. After the page has been decompressed into | |
492 | * the swap cache, the compressed version stored by zswap can be | |
493 | * freed. | |
494 | */ | |
495 | static int zswap_writeback_entry(struct zbud_pool *pool, unsigned long handle) | |
496 | { | |
497 | struct zswap_header *zhdr; | |
498 | swp_entry_t swpentry; | |
499 | struct zswap_tree *tree; | |
500 | pgoff_t offset; | |
501 | struct zswap_entry *entry; | |
502 | struct page *page; | |
503 | u8 *src, *dst; | |
504 | unsigned int dlen; | |
505 | int ret, refcount; | |
506 | struct writeback_control wbc = { | |
507 | .sync_mode = WB_SYNC_NONE, | |
508 | }; | |
509 | ||
510 | /* extract swpentry from data */ | |
511 | zhdr = zbud_map(pool, handle); | |
512 | swpentry = zhdr->swpentry; /* here */ | |
513 | zbud_unmap(pool, handle); | |
514 | tree = zswap_trees[swp_type(swpentry)]; | |
515 | offset = swp_offset(swpentry); | |
516 | BUG_ON(pool != tree->pool); | |
517 | ||
518 | /* find and ref zswap entry */ | |
519 | spin_lock(&tree->lock); | |
520 | entry = zswap_rb_search(&tree->rbroot, offset); | |
521 | if (!entry) { | |
522 | /* entry was invalidated */ | |
523 | spin_unlock(&tree->lock); | |
524 | return 0; | |
525 | } | |
526 | zswap_entry_get(entry); | |
527 | spin_unlock(&tree->lock); | |
528 | BUG_ON(offset != entry->offset); | |
529 | ||
530 | /* try to allocate swap cache page */ | |
531 | switch (zswap_get_swap_cache_page(swpentry, &page)) { | |
532 | case ZSWAP_SWAPCACHE_NOMEM: /* no memory */ | |
533 | ret = -ENOMEM; | |
534 | goto fail; | |
535 | ||
536 | case ZSWAP_SWAPCACHE_EXIST: /* page is unlocked */ | |
537 | /* page is already in the swap cache, ignore for now */ | |
538 | page_cache_release(page); | |
539 | ret = -EEXIST; | |
540 | goto fail; | |
541 | ||
542 | case ZSWAP_SWAPCACHE_NEW: /* page is locked */ | |
543 | /* decompress */ | |
544 | dlen = PAGE_SIZE; | |
545 | src = (u8 *)zbud_map(tree->pool, entry->handle) + | |
546 | sizeof(struct zswap_header); | |
547 | dst = kmap_atomic(page); | |
548 | ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, | |
549 | entry->length, dst, &dlen); | |
550 | kunmap_atomic(dst); | |
551 | zbud_unmap(tree->pool, entry->handle); | |
552 | BUG_ON(ret); | |
553 | BUG_ON(dlen != PAGE_SIZE); | |
554 | ||
555 | /* page is up to date */ | |
556 | SetPageUptodate(page); | |
557 | } | |
558 | ||
b349acc7 WY |
559 | /* move it to the tail of the inactive list after end_writeback */ |
560 | SetPageReclaim(page); | |
561 | ||
2b281117 SJ |
562 | /* start writeback */ |
563 | __swap_writepage(page, &wbc, end_swap_bio_write); | |
564 | page_cache_release(page); | |
565 | zswap_written_back_pages++; | |
566 | ||
567 | spin_lock(&tree->lock); | |
568 | ||
569 | /* drop local reference */ | |
570 | zswap_entry_put(entry); | |
571 | /* drop the initial reference from entry creation */ | |
572 | refcount = zswap_entry_put(entry); | |
573 | ||
574 | /* | |
575 | * There are three possible values for refcount here: | |
576 | * (1) refcount is 1, load is in progress, unlink from rbtree, | |
577 | * load will free | |
578 | * (2) refcount is 0, (normal case) entry is valid, | |
579 | * remove from rbtree and free entry | |
580 | * (3) refcount is -1, invalidate happened during writeback, | |
581 | * free entry | |
582 | */ | |
583 | if (refcount >= 0) { | |
584 | /* no invalidate yet, remove from rbtree */ | |
585 | rb_erase(&entry->rbnode, &tree->rbroot); | |
586 | } | |
587 | spin_unlock(&tree->lock); | |
588 | if (refcount <= 0) { | |
589 | /* free the entry */ | |
590 | zswap_free_entry(tree, entry); | |
591 | return 0; | |
592 | } | |
593 | return -EAGAIN; | |
594 | ||
595 | fail: | |
596 | spin_lock(&tree->lock); | |
597 | zswap_entry_put(entry); | |
598 | spin_unlock(&tree->lock); | |
599 | return ret; | |
600 | } | |
601 | ||
602 | /********************************* | |
603 | * frontswap hooks | |
604 | **********************************/ | |
605 | /* attempts to compress and store an single page */ | |
606 | static int zswap_frontswap_store(unsigned type, pgoff_t offset, | |
607 | struct page *page) | |
608 | { | |
609 | struct zswap_tree *tree = zswap_trees[type]; | |
610 | struct zswap_entry *entry, *dupentry; | |
611 | int ret; | |
612 | unsigned int dlen = PAGE_SIZE, len; | |
613 | unsigned long handle; | |
614 | char *buf; | |
615 | u8 *src, *dst; | |
616 | struct zswap_header *zhdr; | |
617 | ||
618 | if (!tree) { | |
619 | ret = -ENODEV; | |
620 | goto reject; | |
621 | } | |
622 | ||
623 | /* reclaim space if needed */ | |
624 | if (zswap_is_full()) { | |
625 | zswap_pool_limit_hit++; | |
626 | if (zbud_reclaim_page(tree->pool, 8)) { | |
627 | zswap_reject_reclaim_fail++; | |
628 | ret = -ENOMEM; | |
629 | goto reject; | |
630 | } | |
631 | } | |
632 | ||
633 | /* allocate entry */ | |
634 | entry = zswap_entry_cache_alloc(GFP_KERNEL); | |
635 | if (!entry) { | |
636 | zswap_reject_kmemcache_fail++; | |
637 | ret = -ENOMEM; | |
638 | goto reject; | |
639 | } | |
640 | ||
641 | /* compress */ | |
642 | dst = get_cpu_var(zswap_dstmem); | |
643 | src = kmap_atomic(page); | |
644 | ret = zswap_comp_op(ZSWAP_COMPOP_COMPRESS, src, PAGE_SIZE, dst, &dlen); | |
645 | kunmap_atomic(src); | |
646 | if (ret) { | |
647 | ret = -EINVAL; | |
648 | goto freepage; | |
649 | } | |
650 | ||
651 | /* store */ | |
652 | len = dlen + sizeof(struct zswap_header); | |
653 | ret = zbud_alloc(tree->pool, len, __GFP_NORETRY | __GFP_NOWARN, | |
654 | &handle); | |
655 | if (ret == -ENOSPC) { | |
656 | zswap_reject_compress_poor++; | |
657 | goto freepage; | |
658 | } | |
659 | if (ret) { | |
660 | zswap_reject_alloc_fail++; | |
661 | goto freepage; | |
662 | } | |
663 | zhdr = zbud_map(tree->pool, handle); | |
664 | zhdr->swpentry = swp_entry(type, offset); | |
665 | buf = (u8 *)(zhdr + 1); | |
666 | memcpy(buf, dst, dlen); | |
667 | zbud_unmap(tree->pool, handle); | |
668 | put_cpu_var(zswap_dstmem); | |
669 | ||
670 | /* populate entry */ | |
671 | entry->offset = offset; | |
672 | entry->handle = handle; | |
673 | entry->length = dlen; | |
674 | ||
675 | /* map */ | |
676 | spin_lock(&tree->lock); | |
677 | do { | |
678 | ret = zswap_rb_insert(&tree->rbroot, entry, &dupentry); | |
679 | if (ret == -EEXIST) { | |
680 | zswap_duplicate_entry++; | |
681 | /* remove from rbtree */ | |
682 | rb_erase(&dupentry->rbnode, &tree->rbroot); | |
683 | if (!zswap_entry_put(dupentry)) { | |
684 | /* free */ | |
685 | zswap_free_entry(tree, dupentry); | |
686 | } | |
687 | } | |
688 | } while (ret == -EEXIST); | |
689 | spin_unlock(&tree->lock); | |
690 | ||
691 | /* update stats */ | |
692 | atomic_inc(&zswap_stored_pages); | |
693 | zswap_pool_pages = zbud_get_pool_size(tree->pool); | |
694 | ||
695 | return 0; | |
696 | ||
697 | freepage: | |
698 | put_cpu_var(zswap_dstmem); | |
699 | zswap_entry_cache_free(entry); | |
700 | reject: | |
701 | return ret; | |
702 | } | |
703 | ||
704 | /* | |
705 | * returns 0 if the page was successfully decompressed | |
706 | * return -1 on entry not found or error | |
707 | */ | |
708 | static int zswap_frontswap_load(unsigned type, pgoff_t offset, | |
709 | struct page *page) | |
710 | { | |
711 | struct zswap_tree *tree = zswap_trees[type]; | |
712 | struct zswap_entry *entry; | |
713 | u8 *src, *dst; | |
714 | unsigned int dlen; | |
715 | int refcount, ret; | |
716 | ||
717 | /* find */ | |
718 | spin_lock(&tree->lock); | |
719 | entry = zswap_rb_search(&tree->rbroot, offset); | |
720 | if (!entry) { | |
721 | /* entry was written back */ | |
722 | spin_unlock(&tree->lock); | |
723 | return -1; | |
724 | } | |
725 | zswap_entry_get(entry); | |
726 | spin_unlock(&tree->lock); | |
727 | ||
728 | /* decompress */ | |
729 | dlen = PAGE_SIZE; | |
730 | src = (u8 *)zbud_map(tree->pool, entry->handle) + | |
731 | sizeof(struct zswap_header); | |
732 | dst = kmap_atomic(page); | |
733 | ret = zswap_comp_op(ZSWAP_COMPOP_DECOMPRESS, src, entry->length, | |
734 | dst, &dlen); | |
735 | kunmap_atomic(dst); | |
736 | zbud_unmap(tree->pool, entry->handle); | |
737 | BUG_ON(ret); | |
738 | ||
739 | spin_lock(&tree->lock); | |
740 | refcount = zswap_entry_put(entry); | |
741 | if (likely(refcount)) { | |
742 | spin_unlock(&tree->lock); | |
743 | return 0; | |
744 | } | |
745 | spin_unlock(&tree->lock); | |
746 | ||
747 | /* | |
748 | * We don't have to unlink from the rbtree because | |
749 | * zswap_writeback_entry() or zswap_frontswap_invalidate page() | |
750 | * has already done this for us if we are the last reference. | |
751 | */ | |
752 | /* free */ | |
753 | ||
754 | zswap_free_entry(tree, entry); | |
755 | ||
756 | return 0; | |
757 | } | |
758 | ||
759 | /* frees an entry in zswap */ | |
760 | static void zswap_frontswap_invalidate_page(unsigned type, pgoff_t offset) | |
761 | { | |
762 | struct zswap_tree *tree = zswap_trees[type]; | |
763 | struct zswap_entry *entry; | |
764 | int refcount; | |
765 | ||
766 | /* find */ | |
767 | spin_lock(&tree->lock); | |
768 | entry = zswap_rb_search(&tree->rbroot, offset); | |
769 | if (!entry) { | |
770 | /* entry was written back */ | |
771 | spin_unlock(&tree->lock); | |
772 | return; | |
773 | } | |
774 | ||
775 | /* remove from rbtree */ | |
776 | rb_erase(&entry->rbnode, &tree->rbroot); | |
777 | ||
778 | /* drop the initial reference from entry creation */ | |
779 | refcount = zswap_entry_put(entry); | |
780 | ||
781 | spin_unlock(&tree->lock); | |
782 | ||
783 | if (refcount) { | |
784 | /* writeback in progress, writeback will free */ | |
785 | return; | |
786 | } | |
787 | ||
788 | /* free */ | |
789 | zswap_free_entry(tree, entry); | |
790 | } | |
791 | ||
792 | /* frees all zswap entries for the given swap type */ | |
793 | static void zswap_frontswap_invalidate_area(unsigned type) | |
794 | { | |
795 | struct zswap_tree *tree = zswap_trees[type]; | |
0bd42136 | 796 | struct zswap_entry *entry, *n; |
2b281117 SJ |
797 | |
798 | if (!tree) | |
799 | return; | |
800 | ||
801 | /* walk the tree and free everything */ | |
802 | spin_lock(&tree->lock); | |
0bd42136 | 803 | rbtree_postorder_for_each_entry_safe(entry, n, &tree->rbroot, rbnode) { |
2b281117 SJ |
804 | zbud_free(tree->pool, entry->handle); |
805 | zswap_entry_cache_free(entry); | |
806 | atomic_dec(&zswap_stored_pages); | |
807 | } | |
808 | tree->rbroot = RB_ROOT; | |
809 | spin_unlock(&tree->lock); | |
aa9bca05 WY |
810 | |
811 | zbud_destroy_pool(tree->pool); | |
812 | kfree(tree); | |
813 | zswap_trees[type] = NULL; | |
2b281117 SJ |
814 | } |
815 | ||
816 | static struct zbud_ops zswap_zbud_ops = { | |
817 | .evict = zswap_writeback_entry | |
818 | }; | |
819 | ||
820 | static void zswap_frontswap_init(unsigned type) | |
821 | { | |
822 | struct zswap_tree *tree; | |
823 | ||
824 | tree = kzalloc(sizeof(struct zswap_tree), GFP_KERNEL); | |
825 | if (!tree) | |
826 | goto err; | |
827 | tree->pool = zbud_create_pool(GFP_KERNEL, &zswap_zbud_ops); | |
828 | if (!tree->pool) | |
829 | goto freetree; | |
830 | tree->rbroot = RB_ROOT; | |
831 | spin_lock_init(&tree->lock); | |
832 | zswap_trees[type] = tree; | |
833 | return; | |
834 | ||
835 | freetree: | |
836 | kfree(tree); | |
837 | err: | |
838 | pr_err("alloc failed, zswap disabled for swap type %d\n", type); | |
839 | } | |
840 | ||
841 | static struct frontswap_ops zswap_frontswap_ops = { | |
842 | .store = zswap_frontswap_store, | |
843 | .load = zswap_frontswap_load, | |
844 | .invalidate_page = zswap_frontswap_invalidate_page, | |
845 | .invalidate_area = zswap_frontswap_invalidate_area, | |
846 | .init = zswap_frontswap_init | |
847 | }; | |
848 | ||
849 | /********************************* | |
850 | * debugfs functions | |
851 | **********************************/ | |
852 | #ifdef CONFIG_DEBUG_FS | |
853 | #include <linux/debugfs.h> | |
854 | ||
855 | static struct dentry *zswap_debugfs_root; | |
856 | ||
857 | static int __init zswap_debugfs_init(void) | |
858 | { | |
859 | if (!debugfs_initialized()) | |
860 | return -ENODEV; | |
861 | ||
862 | zswap_debugfs_root = debugfs_create_dir("zswap", NULL); | |
863 | if (!zswap_debugfs_root) | |
864 | return -ENOMEM; | |
865 | ||
866 | debugfs_create_u64("pool_limit_hit", S_IRUGO, | |
867 | zswap_debugfs_root, &zswap_pool_limit_hit); | |
868 | debugfs_create_u64("reject_reclaim_fail", S_IRUGO, | |
869 | zswap_debugfs_root, &zswap_reject_reclaim_fail); | |
870 | debugfs_create_u64("reject_alloc_fail", S_IRUGO, | |
871 | zswap_debugfs_root, &zswap_reject_alloc_fail); | |
872 | debugfs_create_u64("reject_kmemcache_fail", S_IRUGO, | |
873 | zswap_debugfs_root, &zswap_reject_kmemcache_fail); | |
874 | debugfs_create_u64("reject_compress_poor", S_IRUGO, | |
875 | zswap_debugfs_root, &zswap_reject_compress_poor); | |
876 | debugfs_create_u64("written_back_pages", S_IRUGO, | |
877 | zswap_debugfs_root, &zswap_written_back_pages); | |
878 | debugfs_create_u64("duplicate_entry", S_IRUGO, | |
879 | zswap_debugfs_root, &zswap_duplicate_entry); | |
880 | debugfs_create_u64("pool_pages", S_IRUGO, | |
881 | zswap_debugfs_root, &zswap_pool_pages); | |
882 | debugfs_create_atomic_t("stored_pages", S_IRUGO, | |
883 | zswap_debugfs_root, &zswap_stored_pages); | |
884 | ||
885 | return 0; | |
886 | } | |
887 | ||
888 | static void __exit zswap_debugfs_exit(void) | |
889 | { | |
890 | debugfs_remove_recursive(zswap_debugfs_root); | |
891 | } | |
892 | #else | |
893 | static int __init zswap_debugfs_init(void) | |
894 | { | |
895 | return 0; | |
896 | } | |
897 | ||
898 | static void __exit zswap_debugfs_exit(void) { } | |
899 | #endif | |
900 | ||
901 | /********************************* | |
902 | * module init and exit | |
903 | **********************************/ | |
904 | static int __init init_zswap(void) | |
905 | { | |
906 | if (!zswap_enabled) | |
907 | return 0; | |
908 | ||
909 | pr_info("loading zswap\n"); | |
910 | if (zswap_entry_cache_create()) { | |
911 | pr_err("entry cache creation failed\n"); | |
912 | goto error; | |
913 | } | |
914 | if (zswap_comp_init()) { | |
915 | pr_err("compressor initialization failed\n"); | |
916 | goto compfail; | |
917 | } | |
918 | if (zswap_cpu_init()) { | |
919 | pr_err("per-cpu initialization failed\n"); | |
920 | goto pcpufail; | |
921 | } | |
922 | frontswap_register_ops(&zswap_frontswap_ops); | |
923 | if (zswap_debugfs_init()) | |
924 | pr_warn("debugfs initialization failed\n"); | |
925 | return 0; | |
926 | pcpufail: | |
927 | zswap_comp_exit(); | |
928 | compfail: | |
929 | zswap_entry_cache_destory(); | |
930 | error: | |
931 | return -ENOMEM; | |
932 | } | |
933 | /* must be late so crypto has time to come up */ | |
934 | late_initcall(init_zswap); | |
935 | ||
936 | MODULE_LICENSE("GPL"); | |
937 | MODULE_AUTHOR("Seth Jennings <sjenning@linux.vnet.ibm.com>"); | |
938 | MODULE_DESCRIPTION("Compressed cache for swap pages"); |